Long-term health and immunity
Vitamin Aand All-cause mortality
Four sources here, and they say different things: one measured lower all-cause mortality, two found no clear difference and one reported mixed results.
How sure anyone can be
High certainty, level 4 of 4Further research is very unlikely to change this.
The most certain of the four findings here; each record carries its own.
The numbers reported
One source’s range, drawn against its own line of no difference and scaled to its own numbers.
0.830.88 risk ratio0.93
This range stays on one side of the no-difference line.
Four sources, newest first
We do not pick between these or average them into one number.
What we read is the published abstract, not the full paper, so a blank below may still be printed in the paper itself. A fixed rule worked this out from the source’s own fields. Nobody checked this rating by hand.
Systematic review, 2022 · 19 studies pooled · 1,202,382 participants
High certainty, level 4 of 4Vitamin A supplementation for preventing morbidity and mortality in children from six months to five years of age.
Cochrane Database Syst Rev. 2022;3(3):CD008524. doi:10.1002/14651858.CD008524.pub4. PMID:35294044.
This source later carried a notice: Update of Cochrane Database Syst Rev. 2017 Mar 11;3:CD008524. doi: 10.1002/14651858.CD008524.pub3. The number below is exactly as the source gave it.
- Number reported
- 0.88 risk ratio
- Which way it went
- Lower
- Likely range
- 0.83 to 0.93
- Source’s own words
- risk ratio for all-cause mortality vs control at longest follow-up
- Who was studied
- Child 6 to 59 months
- Compared with
- control (placebo or no supplementation)
- Amount taken
- Not in the abstract
- For how long
- Not in the abstract
- Disagreement between studies
- Not in the abstract
- Kind of record
- Journal article
How this rating was reachedstarts at High, and nothing brought it down
- Starts at High
- Ends at HighNothing brought this one down a step.
- Checked, nothing to step it down for
- risk of bias, indirectness and imprecision
- Inconsistency
- No high disagreement reported between the 19 studies it pooled
AI-reviewed & signed — an AI agent re-read this finding against the saved source and checked that the quote, the numbers, the units and the direction match it. No person read it. The owner authorised the agent to sign the batch with the owner's key, and every build rechecks that signature against these exact bytes.
Systematic review, 2019 · 11 studies pooled
Very low certainty, level 1 of 4Early neonatal vitamin A supplementation and infant mortality: an individual participant data meta-analysis of randomised controlled trials.
Arch Dis Child. 2019;104(3):217-226. doi:10.1136/archdischild-2018-315242. PMID:30425075.
- Number reported
- 0.97 risk ratio
- Which way it went
- Mixed results
- Likely range
- 0.89 to 1.06
- Source’s own words
- risk ratio for mortality through 6 months of age vs placebo
- Who was studied
- Neonate
- Compared with
- placebo
- Amount taken
- Not in the abstract
- For how long
- Not in the abstract
- Disagreement between studies
- Not in the abstract
- Kind of record
- Journal article
How this rating was reachedstarts at High, 3 steps down: risk of bias, imprecision and inconsistency
- Starts at High
- Risk of bias brought it down to Moderatethe abstract reports no risk-of-bias or quality appraisal, so study limitations cannot be ruled outNot in the abstract
- Imprecision brought it down to Lowthe confidence interval includes no effectReported in the abstract
- Inconsistency brought it down to Very lowpooled studies disagree on the direction of effectReported in the abstract
- Ends at Very low3 steps down.
- Checked, nothing to step it down for
- indirectness
Imprecision stops at the first check that applies; others may apply too.
AI-reviewed & signed — an AI agent re-read this finding against the saved source and checked that the quote, the numbers, the units and the direction match it. No person read it. The owner authorised the agent to sign the batch with the owner's key, and every build rechecks that signature against these exact bytes.
Systematic review, 2016 · 7 studies pooled · 21,339 participants
Moderate certainty, level 3 of 4Vitamin A supplementation for the prevention of morbidity and mortality in infants one to six months of age.
Cochrane Database Syst Rev. 2016;9(9):CD007480. doi:10.1002/14651858.CD007480.pub3. PMID:27681486.
- Number reported
- 1.05 risk ratio
- Which way it went
- No clear difference
- Likely range
- 0.89 to 1.25
- Source’s own words
- risk ratio for all-cause mortality vs control
- Who was studied
- Infant 1 to 6 months
- Compared with
- placebo or no intervention
- Amount taken
- Not in the abstract
- For how long
- Not in the abstract
- Disagreement between studies
- I2 = 0%
- Kind of record
- Journal article
How this rating was reachedstarts at High, one step down: imprecision
- Starts at High
- Imprecision brought it down to Moderatethe confidence interval includes no effectReported in the abstract
- Ends at ModerateOne step down.
- Checked, nothing to step it down for
- risk of bias and indirectness
- Inconsistency
- No high disagreement reported between the 7 studies it pooled
Imprecision stops at the first check that applies; others may apply too.
AI-reviewed & signed — an AI agent re-read this finding against the saved source and checked that the quote, the numbers, the units and the direction match it. No person read it. The owner authorised the agent to sign the batch with the owner's key, and every build rechecks that signature against these exact bytes.
Systematic review, 2013
Moderate certainty, level 3 of 4Meta-regression analyses, meta-analyses, and trial sequential analyses of the effects of supplementation with beta-carotene, vitamin A, and vitamin E singly or in different combinations on all-cause mortality: do we have evidence for lack of harm?
PLoS One. 2013;8(9):e74558. doi:10.1371/journal.pone.0074558. PMID:24040282.
- Number reported
- 1.08 risk ratio
- Which way it went
- No clear difference
- Likely range
- 0.98 to 1.19
- Source’s own words
- risk ratio for all-cause mortality, vitamin A above the RDA vs control
- Who was studied
- Adult
- Compared with
- placebo or no intervention
- Amount taken
- 800 ug/d (doses above the RDA) (upper bound: Not in the abstract)
- For how long
- Not in the abstract
- Disagreement between studies
- I(2) = 53%
- Kind of record
- Journal article
How this rating was reachedstarts at High, one step down: imprecision
- Starts at High
- Imprecision brought it down to Moderatethe confidence interval includes no effectReported in the abstract
- Ends at ModerateOne step down.
- Checked, nothing to step it down for
- risk of bias and indirectness
- Inconsistency
- No disagreement reported, and no count of studies behind it
Imprecision stops at the first check that applies; others may apply too.
AI-reviewed & signed — an AI agent re-read this finding against the saved source and checked that the quote, the numbers, the units and the direction match it. No person read it. The owner authorised the agent to sign the batch with the owner's key, and every build rechecks that signature against these exact bytes.
What is still missing from these readings
- Two do not say how many people took part.
- Amount taken — Three of Four readings: Not in the abstract.
- For how long — Not in the abstract.
Something nobody wrote down is never a zero and never a guess.
Nothing left on our list for Vitamin A
All two things on our list for Vitamin A have been read. That is rare here.
Still to read means nobody here has got to it, not that it was tried and did nothing or that no research exists. A pairing on no list is not a gap: we never set out to read it.
Read next
Vitamin A
One other question read for it
Long-term health and immunity
20 questions read under it
All-cause mortality
Nine other ingredients read against it
First six, alphabetical, and by nothing else. The rest are on Long-term health and immunity.
This is a library, not advice. No recommendation, no dose, no diagnosis, no ranking. We never ask about your symptoms, and nothing here is tailored to you.